/* global styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #ffffff;
}

a {
    text-decoration: none;
    color: inherit;
}

/* color variables */
:root {
    --primary-blue: #1a5276;
    --light-blue: #3498db;
    --dark-blue: #0d3347;
    --white: #ffffff;
    --light-gray: #f5f7fa;
    --medium-gray: #e0e5ec;
}

/* navigation */
.navbar {
    background-color: var(--primary-blue);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.nav-brand a {
    color: var(--white);
    font-size: 1.5rem;
    font-weight: bold;
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: var(--white);
    font-size: 1rem;
    padding: 0.5rem 1rem;
    border-radius: 5px;
}

.nav-links a:hover,
.nav-links a.active {
    background-color: var(--light-blue);
}

/* hero section */
.hero {
    background: linear-gradient(135deg, var(--primary-blue), var(--light-blue));
    color: var(--white);
    text-align: center;
    padding: 6rem 2rem;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.hero p {
    font-size: 1.25rem;
    opacity: 0.9;
}

/* page headers */
.page-header {
    background: linear-gradient(135deg, var(--primary-blue), var(--light-blue));
    color: var(--white);
    text-align: center;
    padding: 4rem 2rem;
}

.page-header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

.page-header p {
    font-size: 1.1rem;
    opacity: 0.9;
}

/* sections */
section {
    padding: 4rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

section h2 {
    color: var(--primary-blue);
    font-size: 2rem;
    margin-bottom: 1.5rem;
    text-align: center;
}

/* about us section */
.about {
    background-color: var(--white);
}

.about p {
    max-width: 800px;
    margin: 0 auto 1rem auto;
    text-align: center;
    font-size: 1.1rem;
}

.inline-link {
    color: var(--light-blue);
    font-weight: 600;
}

.inline-link:hover {
    color: var(--primary-blue);
    text-decoration: underline;
}

/* team leads section */
.leads {
    background-color: var(--light-gray);
}

.leads-container {
    display: flex;
    justify-content: center;
    gap: 3rem;
    flex-wrap: wrap;
}

.lead-card {
    background-color: var(--white);
    border-radius: 10px;
    padding: 2rem;
    text-align: center;
    max-width: 350px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.lead-image {
    width: 150px;
    height: 150px;
    border-radius: 50%;
    overflow: hidden;
    margin: 0 auto 1.5rem auto;
    border: 4px solid var(--light-blue);
}

.lead-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.lead-card h3 {
    color: var(--primary-blue);
    margin-bottom: 0.5rem;
}

.lead-title {
    color: var(--light-blue);
    font-weight: 600;
    margin-bottom: 1rem;
}

.lead-bio {
    color: #666;
    font-size: 0.95rem;
    text-align: left;
}

/* join us section */
.join-us {
    background-color: var(--white);
    text-align: center;
}

.join-us p {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
}

.contact-email {
    background-color: var(--light-gray);
    padding: 2rem;
    border-radius: 10px;
    display: inline-block;
}

.email-link {
    color: var(--light-blue);
    font-size: 1.25rem;
    font-weight: 600;
}

.email-link:hover {
    color: var(--primary-blue);
}

/* presentations page section */
.presentations-section {
    background-color: var(--white);
}

.presentations-section.past {
    background-color: var(--light-gray);
}

.section-description {
    text-align: center;
    color: #666;
    margin-bottom: 2rem;
}

.presentations-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    max-width: 900px;
    margin: 0 auto;
}

.presentation-card {
    display: flex;
    background-color: var(--white);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.1);
}

.presentations-section.past .presentation-card {
    background-color: var(--light-gray);
    border: 1px solid var(--medium-gray);
}

.presentation-date {
    background-color: var(--primary-blue);
    color: var(--white);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-width: 100px;
}

.presentation-date .month {
    font-size: 0.9rem;
    text-transform: uppercase;
}

.presentation-date .day {
    font-size: 2rem;
    font-weight: bold;
}

.presentation-date .year {
    font-size: 0.85rem;
}

.presentation-details {
    padding: 1.5rem;
    flex: 1;
}

.presentation-details h3 {
    color: var(--primary-blue);
    margin-bottom: 0.5rem;
}

.presenter {
    color: var(--light-blue);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.description {
    color: #666;
    font-size: 0.95rem;
    font-style: italic;
    margin-top: 0.5rem;
}

.watch-link {
    display: inline-block;
    margin-top: 0.75rem;
    color: var(--primary-blue);
    font-weight: 600;
}

.watch-link:hover {
    color: var(--light-blue);
}

/* videos page section */
.videos-section {
    background-color: var(--light-gray);
    padding: 4rem 2rem;
}

.videos-container {
    display: flex;
    flex-direction: column;
    gap: 3rem;
    max-width: 1000px;
    margin: 0 auto;
}

.video-card {
    background-color: var(--white);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.video-card.full-width {
    max-width: 100%;
}

.video-wrapper {
    position: relative;
    padding-bottom: 56.25%;
    height: 0;
    overflow: hidden;
}

.video-wrapper iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
}

.video-info {
    padding: 2rem;
}

.video-info h3 {
    color: var(--primary-blue);
    margin-bottom: 0.5rem;
    font-size: 1.3rem;
}

.video-date {
    color: var(--light-blue);
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
    font-weight: 600;
}

.video-description {
    color: #666;
    font-size: 0.95rem;
    margin-bottom: 1rem;
}

/* presenters section (within the video card) */
.presenters-section {
    background-color: var(--light-gray);
    border-radius: 10px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
}

.presenters-section h4 {
    color: var(--primary-blue);
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

.presenters-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.presenter-card {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    background-color: var(--white);
    padding: 1rem;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.presenter-image {
    width: 70px;
    height: 70px;
    border-radius: 50%;
    overflow: hidden;
    flex-shrink: 0;
    border: 3px solid var(--light-blue);
    background-color: var(--medium-gray);
}

.presenter-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.presenter-info h5 {
    color: var(--primary-blue);
    margin-bottom: 0.25rem;
    font-size: 1rem;
}

.presenter-info p {
    color: #666;
    font-size: 0.85rem;
    line-height: 1.4;
}

.download-btn {
    display: inline-block;
    background-color: var(--primary-blue);
    color: var(--white);
    padding: 0.75rem 1.5rem;
    border-radius: 5px;
    font-weight: 600;
}

.download-btn:hover {
    background-color: var(--light-blue);
}

/* footer */
.footer {
    background-color: var(--dark-blue);
    color: var(--white);
    text-align: center;
    padding: 2rem;
}

/* responsive design (for different screen sizes) */
@media (max-width: 768px) {
    .navbar {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-links {
        gap: 1rem;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .leads-container {
        flex-direction: column;
        align-items: center;
    }

    .presentation-card {
        flex-direction: column;
    }

    .presentation-date {
        flex-direction: row;
        gap: 0.5rem;
        padding: 1rem;
    }

    .presentation-date .day {
        font-size: 1.5rem;
    }

    .presenters-grid {
        grid-template-columns: 1fr;
    }

    .presenter-card {
        flex-direction: column;
        text-align: center;
        align-items: center;
    }
}